Welding Arc

Welding Arc

 

an electric arc formed in the weld zone joint or in the area of thermal cutting when an electric current passes between electrodes through a gas. A welding arc is the most developed form of electric discharge in gases. It is characterized by a low voltage, a high current, and the presence of an ionized gas in the arc gap. The ionized gas column of the arc discharge glows brightly and has a temperature of 6,000°-10,000°C along the axis of the arc column. The principal factor responsible for ionization is the high temperature maintained by the flow of energy from a power supply.

The voltage of a welding arc, that is, the voltage between the electrode tips, depends mainly on the length of the arc, the strength of the current, the materials and dimensions of the electrodes, the gas composition, and gas pressure. The properties of a welding arc are controlled by changing the length of the arc (between 0.01 and 1 cm), the strength of the current (between 0.5 and 3,000 amperes), the pressure of the gas (between 102 and 105 newtons/m2, that is, between 0.001 and 1 kg force/cm2), or the material, shape, or dimensions of one of the electrodes. In addition, the arcing zone can be shielded by the flow of a gas, or the arc can be compressed.

The thermal power of a welding arc ranges from 10 to 105 watts at concentrations from 102 to 105 watts/cm2. The wide power range makes it possible to use welding arcs to weld and cut various materials ranging in thickness from 0.05 to 100 mm in one or more passes.

G.I. LESKOV

References in periodicals archive ?
An experimental study on the effect of increased pressure on MIG welding arc, International Journal of Applied Engineering Research 2(1): 22-27.
Three design focus areas help to deliver a precise welding arc.
Thanks to high open circuit voltage and a very stable welding arc, users can weld all types of coated electrode.
Smart-Cor technology provides independent weld and generator power, ensuring no interaction between the welding arc and jobsite tools such as grinders and chop saws.
Novel welding processes with lower heat input, based on pulsed welding arc, may effectively be used for fabrication of sheet metal products, reducing the problems related to the MIG process.
Welding arc here represents a concentrated high intense heat which contains localized ions (anions and cations) that would sustain the thermal cycle during the period of the welding process.
The welding arc is considered for the concentrated (spot) heat source, which are moving on welded material by constant velocity.
It turned out that it was impossible to use ingenious development of Wenelt in cathodes of welding electric arc, because for stable work of the welding arc it is necessary that mean density of current on the surface of a non-consumable cathode of welding arc, in addition to the current density in the cathode spot, exceeded mentioned density in the tubes at least by three orders [4].
One such development is Waveform Control Technology[TM], which Lincoln Electric has developed to provide real-time manipulation of the welding arc to achieve specified and controllable results.
Since the late 1970s, researchers have known that laser beams could be used to create a path of electrons for arcs to follow, but generating enough electrons to attract a welding arc always required a high-power laser and a high-temperature laser beam path.